1. Field of Invention
The present invention relates to a pump and, more particularly, a pump for providing three modes of pumping.
2. Related Prior Art
Cycling is a popular sport. Some people ride mountain bicycles in mountain areas. Some other people ride racing bicycles around tracks. Although not common, some other people ride general-purpose bicycles for everyday short-range transportation in cities. The bicycle includes various tires. The tires all must be pumped but require different standards of pressure. Some of the bicycles are each equipped with one or two cushions. To pump the various tires and cushions, there are devised various pumps. A shop or workshop is forced to buy various pumps for pumping various tires and cushions.
Disclosed in Taiwanese Patent Publication No. 524274 is a pump for pumping at a high pressure and at a high rate. The conventional pump includes a base 10, a first cylinder 30 installed on the base 10, a second cylinder 51 inserted in the first cylinder 30, a piston 53 attached to the second cylinder 51, a third cylinder 40 inserted in the second cylinder 51 through the piston 53, a piston 41 attached to the third cylinder 40 and a regulator 20 for accumulating air in the second cylinder 51.
Several problems have been encountered during the use of the conventional pump. Firstly, it provides only two pressures, and two pressures are not enough for various tires and cushions. An additional pump is required for pumping a tubular tire or a cushion. For a rider, it is inconvenient to carry a pump for tires and another pump for cushions.
Secondly, the assembly of the cylinders in a telescopic manner is complicated and, hence, expensive.
Thirdly, it is vulnerable to leaks, since the cylinders are assembled in the telescopic manner.
Fourthly, a user cannot hold it in position, since it fails to provide adequate treads for the user's feet.
The present invention is therefore intended to obviate or at least alleviate the problems encountered in the prior art.